Icefalls

Icefalls are a type of glacier feature where moving ice flows over a steep bed or cliff, causing chaotic fragmentation and a cascade of ice blocks that resembles a frozen waterfall. They are not simply frozen waterfalls; they are active ice flows. They form where a glacier encounters abrupt topography, such as bedrock steps, chutes, or hanging valleys, forcing the ice to bend and shear. The result is rapid crevassing, the buildup of tall seracs, and sometimes streaming meltwater that refreezes in cracks. Icefalls are highly dynamic, with the ice surface continually reorganizing as flow rates and temperature change.

Common features include crevasses, seracs, and bergschrunds; the structure is unstable, and ice blocks can collapse without warning. Hidden crevasses covered by snow bridges pose serious danger to climbers and expeditions. Icefalls can also shift the surrounding terrain, contribute to rockfall, and alter the downstream glacier flow.

Geographically, icefalls occur in many large mountain glaciers around the world, especially in the Himalayas, Alaska Range, Karakoram, and the Andes. The Khumbu Icefall near Mount Everest is among the most famous, serving as an early and precarious section on many expeditions. Icefalls may advance or retreat with the glacier and are sensitive to seasonal temperature and meltwater inputs.

Scientists study icefalls to understand glacier dynamics, calving processes, and hydrology. Changes in the size or activity of an icefall can indicate shifts in glacier velocity and health under climate change. Management and safety practices for mountaineering often focus on routes through icefalls, using ropework and monitoring for icefall instability.